"We are in chasms and gorges where even satellite phone would actually have a lot of trouble because you can't see enough of the sky to acquire the satellite."

Gardner-Stephen says the device incorporates a compact version of a mobile phone tower into the phone itself.

"So using the wi-fi interface that is in many phones today that you would normally use for internet or that kind of thing, we are actually carrying voice over that, but in a way that doesn't need to go back to a central repository anywhere," he says.

The signal between phones is limited to a few hundred metres, but by adding more devices and small transmitters the range can be expanded to cover a much bigger area.

Gardner-Stephen says the system combines voice over IP technology (VoIP) with wi-fi to form a daisy chain form of communication.

"The trick is with your regular VoIP you need an internet connection like a hotspot or access point," he says. "We've set up the phones in something called ad-hoc mode so the phones will basically talk to anything that is within range of them.

"If you had 10 phones in a row, 5 kilometres long, that's well beyond the individual radio range of each phone. [This system] will actually make sure that the call gets carried through all the phones to the other end."

Disaster network

Gardner-Stephen says the system could provide an instant mobile phone network in a disaster.

"With Haiti what was actually observed was that their mobile phone network and their landline phone network was essentially knocked out for the first 48 hours after the earthquake," he says.

"It was really about a week before it was back to the point where people could fairly readily make calls.

"If we can provide [local people] with ease of communications as soon as possible after the earthquake, not 48 hours, not 72 hours but potentially minutes after a disaster, then we can help them to start rescuing people from rubble and generally rebuilding, maintaining law and order.

Gardner-Stephen says this recent test near Arkaroola has proven that the network can be deployed at low-cost, in a short space of time.

He says the next step for the researchers is to increase range, improve sound quality and develop a way of air dropping the system into a disaster zone.